The WA parliamentary question addresses concerns about acid sulphate soil contamination from accessing the South West Yarragadee aquifer. The government assures that studies indicate no measurable drawdown and further investigations will be conducted.

AnsweredQoN 569Legislative Assembly
Asked
7 March 2006
Portfolio
Water Resources

QuestionView source ↗

(b) as the precursor to acid sulphate soil is a lowering of the water level of coastal wetland areas, what environmental safeguards is the Government considering using to avoid the final trigger to acid sulphate contamination; and (c) if there are no definitive studies in place, will the Government conduct a thorough investigation of the potential threat to the Swan Coastal Plain environment before proceeding with any plan to access the South West Yarragadee?
(c) if there are no definitive studies in place, will the Government conduct a thorough investigation of the potential threat to the Swan Coastal Plain environment before proceeding with any plan to access the South West Yarragadee?
(b) The studies conducted by the Water Corporation, which have considered the effects after 30 years of pumping, show that there is no measurable drawdown expected in the shallow geological formations close to the coast where there is a high risk of acid sulphate soil generation. Monitoring of water quality and water levels will be undertaken at a large number of sites, and a stakeholder-based monitoring review group is proposed to independently review and provide public advice on the monitoring results. (c) While a regional risk assessment of actual acid sulphate soils and potential acid sulphate soils has already been undertaken, as part of the proposal the Water Corporation has committed to undertaking further studies of potentially vulnerable areas on the Swan and Scott coastal plains. This would further our understanding of the occurrence, spatial extent and depth of acid sulphate soils, and further improve management responses.
(c) While a regional risk assessment of actual acid sulphate soils and potential acid sulphate soils has already been undertaken, as part of the proposal the Water Corporation has committed to undertaking further studies of potentially vulnerable areas on the Swan and Scott coastal plains. This would further our understanding of the occurrence, spatial extent and depth of acid sulphate soils, and further improve management responses.

AnswerView source ↗

Answered
4 April 2006
Responded by
Minister for Water Resources
Response time
28 days
(a) The Sustainability Evaluation / Environmental Review and Management Programme report for the South West Yarragadee water supply proposal includes an extensive discussion on the potential for acid sulphate soil creation as a result of the proposal, on both the Swan and Scott Coastal Plains. Assessment of the potential for impacts uses mapping of acid sulphate soil risk areas on the Swan Coastal Plain, prepared by the Western Australian Planning Commission and the Department of Environment.
(b) The studies conducted by the Water Corporation, which have considered the effects after 30 years of pumping, show that there is no measurable drawdown expected in the shallow geological formations close to the coast where there is a high risk of acid sulphate soil generation. Monitoring of water quality and water levels will be undertaken at a large number of sites, and a stakeholder-based monitoring review group is proposed to independently review and provide public advice on the monitoring results.
(c) While a regional risk assessment of actual acid sulphate soils and potential acid sulphate soils has already been undertaken, as part of the proposal the Water Corporation has committed to undertaking further studies of potentially vulnerable areas on the Swan and Scott coastal plains. This would further our understanding of the occurrence, spatial extent and depth of acid sulphate soils, and further improve management responses.

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